fix(smartmetrics): Refactor metrics calculation and update Prometheus integration documentation

readme.hints.md

@@ -1 +1,30 @@
- 
+# SmartMetrics Implementation Hints
+
+## Prometheus Integration
+
+The package now supports exposing metrics in Prometheus format through two mechanisms:
+
+1. **Direct Export**: `getPrometheusFormattedMetrics()` returns metrics in Prometheus text exposition format
+2. **HTTP Endpoint**: `enablePrometheusEndpoint(port)` starts an HTTP server that exposes metrics on `/metrics`
+
+### Architecture Decisions
+
+- We use the prom-client library's default collectors for standard Node.js metrics
+- Custom gauges are created for our calculated metrics (CPU percentage, memory percentage, memory bytes)
+- The `getMetrics()` method calculates values directly rather than parsing the Prometheus registry JSON
+- For metrics like `nodejs_active_handles_total` and `nodejs_active_requests_total`, we return 0 in `getMetrics()` since these require deprecated Node.js APIs, but the Prometheus collectors still track the real values
+
+### Consolidation Approach
+
+Initially, we were mixing two approaches:
+1. Extracting values from the Prometheus registry JSON for default metrics
+2. Creating custom gauges for calculated metrics
+
+We consolidated by:
+- Calculating all values directly in `getMetrics()` where possible
+- Only using the Prometheus registry for the text exposition format
+- This eliminates the dependency on parsing registry JSON and makes the code cleaner
+
+### Memory Calculation
+
+The package tracks memory usage across the main process and all child processes using `pidtree` and `pidusage`. This provides a more comprehensive view than just the main process memory.